Lily Krakowski on tue 14 oct 03
Whether one tests a glaze empirically or by calculation or by this or that
is a personal decision, and much goes into it.
But several things remain "givens", and one might as well fit them into
one's glaze testing repertoire from the get-go.
1. Glaze materials are mined, mine runs vary. Ingredients can come from
one country/place/mine or several. Therefore it is important to KEEP a bit
of the former batch of any material identified and dated, and, preferably
with supplier name, on hand, so that if the test of the glaze with the NEWLY
ACQUIRED material tanks, one has a way to double check. Did one err? Did
the material "change"?
2. The strongest influence on a glaze is the body underneath. Therefore
one should test all new glazes on several clay bodies in the range, and one
should test them on those bodies over a bit of white slip. Please remember
that the clay body supplier represents the body he is selling as a buff
body, ideal for throwing, ideal at c 4-8, blah blah blah. HE DOES NOT claim
that all the ingredients IN the body are the same as they were in the last
batch. All of us oldies remember bodies made with Fetzer, Dalton, Jordan
etc--the bodies may still be sold under the same names, but the ingredients
I name no longer exist. By all means keep a dozen test tiles of the OLD
BATCH OF THE BODY on hand to test with if the glazes do not perform on the
new batch.
3. Water. Not mentionned often enough. Yes, water varies from place to
place ,and, as Snail explained, a lot of lime in the water will not cause
lime pops, because only lumps of lime will. However it is wise to have some
distilled water on hand, again, to test glazes that do not perform as
expected.
4. Method of application. Not a huge factor but it is good to rest
"received" glazes that do not perform as expected by several methods of
application.
These are the routine things one does, automatically, so that they are not
mentionned in books nor in the general chitchat....
Lili Krakowski
Constableville, N.Y.
Be of good courag
| |
|
